Think long and hard about getting this groupset if you have a bike with internal cable routing. Even on an externally routed bike in my opinion, shifting is sluggish and imprecise compared to 7800. On my Fondriest TF2 with internal routing, it was horrendous.

It is the first groupset I've ever had problems meching myself. Local mechanics had just as many problems.

I notice posters saying 'well if you mech it right, you have no problems'. Fair enough, but if I (a pretty handy mech) have to spend time on this groupo when I know I can have Sram Red or 7800 dialled in a quarter of the time, tell me why I need to bother? It's a simple decision for me.. the low maintenance, no crap groupo! DA 7900 is sadly neither of these.

I've moved on Sram red now, with 7800 on my other bike. I no longer have nightmares.

My opinion.. if you have an externally routed bike, this group is ok but not of 7800 quality when it comes to rear shifting. Same can be said for Ultegra 6700 vs 6600 in my opinion. Shimano just haven't done the hidden cables well!

If you have an internally routed frame, steer clear, just like Cervelo test team did.

Strengths: Performs faultlessly. Good value for money (with some ultegra parts). It just works. All I need it to do. I quite like the looks, but not really that important to me (rather be riding than admiring)

Weaknesses: Cant think of anything.

Bottom Line:

Well, finally bit the bullet and upgraded from DA 9 spd shifters and ultegra/105 everything else, to DA 7900 shifters, front mech and chain/ultegra everything else (couldnt justify/afford complete DA). Well put it all on my bike last weeka dn then got sick, feeling better by racing on sunday. Did a monor fiddle with micro-adjust before start and then went racing. Thought it maybe a fatal error but WOW, what an improvement. I had no missed shift whatever (even though roads are rough as guts around here), much less force required to make shifts than previous setup. Front shifting is off the planet. So easy and quick, braking is awesome and rear shifting effortless. I cannot see what people are complaining about. I'm no expert mechanic, but I had no trouble doing setup to my normal method, and apart from the initial adjustment when i got on initially (i dont have a workshop stand, so have to do it with the bike upside down) to the rear shifting had no malfunctions of any kind. I havent tried Sram or Campag, have always run shimano on all my bikes (road and MTB) and have never had any problems with it whatsoever. Would highly recommend this setup to any one. The hidden cables are a nice touch, and I found the shifters to be very comfortable (much less numb hands than I normally get). The BB area is also noticably stiffer than before. I am also running Shimano DA carbon clinchers and find these unbelievably good.

Reading the above 10 "reviews" as a professional mechanic, makes me cringe. To say DA 7900 doesn't shift well (for you, on your bike) is ridiculous. Set-up, regardless of what gruppo you run, is crucial. Most people (mechanics included) don't get everything right the first time they assemble a bike. Add a bit of break-in time, and ALL shifting systems need adjustment and re-evaluation to work their best. If ANY aspect of the set-up is off even just a millimeter or two, the shifting precision is compromised. I would be willing to bet, if properly set-up, the negative opinions of at least half of the "reviewers" here would be altered for the better.

Before you slam the best component group money can buy, get a better mechanic.

Weaknesses: Takes more force to actuate levers for shifting. Because of close shifting tolerances, cable routing is very critical, almost requiring the precision of rocket design. Not a lot of room in cabling slop to get the drive train to function well. I'll be swapping this out for SRAM Red on one my bikes. Shifting will not be as quick/precise with Red, but at least it'll shift when I want it to. Brakes on SRAM Red aren't quite as nice, but close enough to get the nod over the 7900 groupset. I also don't need an iron fist on Red to work the shifters.

Bottom Line:

This groupset works shifts very precise, smooth, and quick, although actuating the levers takes more force than the 7800 groupset.

The close tolerances are a blessing and a curse. I have this groupset on two different bikes (same make but different geometry), but on one, it acts very tempermental as it hangs on a couple cogs while shifting to lower gears. On the same bike I have problems, the front derailleur rubs on the chain in spite of adjusting it every which way possible. Trim on the front derailleur would've been nice.

The brakes are EXCELLENT! Cosmetically, I have no issues except for the black anodized part of the cranks which can get nicked up with dings becoming more visible.